Colorado Agriscience Curriculum
Section:
Plant & Soil Science
Unit:
Plant Science Technology
Lesson Number:
10
Lesson Title:
Energy Flow within an Ecosystem
Colorado Agricultural Education Standards:
Standard ESC11/12.10 The student will demonstrate understanding of the principles of
natural resource management in the context of systematics.
Competency ESC11/12.10.01 Understand how systems interact and principles of
natural and artificial fluctuations in ecological systems.
Colorado Science Standards:
Standard 3.1 Students know and understand the characteristics of living things, the
diversity of life, and how living things interact with each other and with their
environment.
Benchmark 3.1.4 Explain how changes in an ecosystem affect biodiversity and
how biodiversity contributes to an ecosystem’s stability.
Benchmark 3.1.5 Analyze the dynamic equilibrium of ecosystems, including
interactions among living and non-living components.
Student Learning Objectives (Enablers)
As a result of this lesson, the student will …
Objective #1 Understand the flow of energy.
Objective #2 Understand the importance of the water cycle to an ecosystem.
Objective #3 Understand the importance of the carbon cycle to an ecosystem.
Objective #4 Understand the importance of the nitrogen cycle to the ecosystem.
Time: Instruction time for this lesson: Two lessons at 50 minutes each
Resources:
Agriscience Fundamentals & Applications Third Edition
Chemical Carousel - A Trip Around the Carbon Cycle
http://library.thinkquest.org/11226/
Unit 1, Lesson 9: Environment, Ecology and Ecosystems
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Resources (continued):
NASA's Conservatorium Hydrologic Cycle
http://observe.arc.nasa.gov/nasa/earth/hydrocycle/hydro1.html
University of Missouri Extension - Nitrogen in the Environment: Nitrogen Cycle
http://muextension.missouri.edu/explore/envqual/wq0252.htm
http://www.kidzone.ws/water/index.html
http://muextension.missouri.edu/xplor/envqual/wq0252.htm
Tools, Equipment, and Supplies
PSSPST9&10 Student Handout #1 – 1 for each student
Key Terms.
Ecosystem
Producers
Consumers
Decomposers
Water Cycle
Carbon Cycle
Nitrogen Cycle
Interest Approach
In a previous lesson an ecosystem was explained as a complex network of living and non
living organisms.
For a network to be called an ecosystem, each organism is affected by other organisms.
This lesson will help you to understand more about how living things depend upon other
living things for the energy they need to live.
The nature of the ecosystem depends greatly on the amount of energy available.
Summary of Content and Teaching Strategies
Objective 1. Understand the flow of energy.
There are three types of organisms that make the ecosystem work. They are producers,
consumers, and decomposers.
PRODUCERS capture solar energy from the sun to produce food used to support life.
Proceed to next slide on U1L10 PowerPoint.
Unit 1, Lesson 9: Environment, Ecology and Ecosystems
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They do this with a process called photosynthesis. This process depends on the green
pigment found in plants called chlorophyll.
Proceed to next slide on U1L10 PowerPoint.
Plants first use energy they produce to grow. Then other organisms that eat plant material
also draw energy from the process.
Proceed to next slide on U1L10 PowerPoint.
Plants used for grain, fruit or vegetables are examples of producer organisms.
CONSUMERS depend upon other organisms to produce the food and energy they need to
live unlike producers plants; consumer organisms are not able to manufacture their own
food.
Consumers include humans, animals, birds and fish.
DECOMPOSERS are the clean-up crew.
They break down waste products and organisms that have died, converting them into
useful chemicals which are released into the soil, air and water.
Decomposers include microorganisms such as bacteria and fungi.
Producer organisms can then use these chemicals to generate new forms of food.
The process by which energy flows from decomposers and producers to consumers and
back to decomposers is called a food chain.
Each food chain is just one possible route by which energy flows.
Proceed to next slide on U1L10 PowerPoint.
This drawing is from southwestern Alaska, in this ecosystem

the vegetation gets energy from the sun

the caribou gets energy from the vegetation

the person gets energy from the caribou.
This is a food chain.
Unit 1, Lesson 9: Environment, Ecology and Ecosystems
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Crayon Moment
Draw your local ecosystem here.
(i) Include the physical features, animals, and plants that you listed for your ecosystem).
(ii) Make sure each animal or plant in your community has a place to live in the habitat).
A food web is the combination of all the possible food chains within an ecosystem.
Energy that flows through an ecosystem must be constantly replenished.
The chemicals used to produce that energy, however, are used over and over again as they
cycle between and among organisms.
Three important substances that help to make an ecosystem work are water, carbon, and
nitrogen. Each of these three has its own unique cycle.
We will go a little more into depth with these unique cycles which are part of the
ecosystem during our next class period.
Review with students the important concepts covered in this lesson!
Day 2
This is a natural break in the lesson if you are on 50 minute blocks. If you are in 90 minute
blocks, continue with the lesson, utilizing the interest approach as a nice break up of
information.
Interest Approach
Get a glass of water and put it on the table next to you. Take a good long look at the water.
Now -- can you guess how old it is?
The water in your glass may have fallen from the sky as rain just last week, but the water itself
has been around pretty much as long as the earth has!
When the first fish crawled out of the ocean onto the land, your glass of water was part of that
ocean. When the Brontosaurus walked through lakes feeding on plants, your glass of water was
part of those lakes. When kings and princesses, knights and squires took a drink from their
wells, your glass of water was part of those wells.
And you thought your parents were OLD
Unit 1, Lesson 9: Environment, Ecology and Ecosystems
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When you look at the whole earth as an ecosystem there are some cycles that become very
importance on a global scale. We will discuss three cycles which are essential to keeping the
earth’s ecosystem in balance.
As you might have guessed the first cycle we will discuss is the water cycle.
Objective 2. Understand the water cycle.
Give Student Handout to kids to color or fill in as you explain each of the parts of the water
cycle.
The water cycle, also known as the hydrologic cycle, is essential to life on earth. An
estimated 90 percent of water on earth is in oceans and polar ice caps.
The water cycle circulates water through all of the world’s ecosystems.
Proceed to next slide on U1L10 PowerPoint.
Water evaporates from the ocean, lakes, streams, wetlands and even puddles to form and
release water vapor into the atmosphere.
Do plants sweat?
Well, sort of.... people perspire (sweat) and plants transpire.
Proceed to next slide on U1L10 PowerPoint.
Transpiration is the process by which plants lose water out of their leaves.
Transpiration gives evaporation a bit of a hand in getting the water vapor back up into the
air.
Water is transpired into water vapor from the leaves of plants.
Proceed to next slide on U1L10 PowerPoint.
Water vapor in the air gets cold and changes back into liquid, forming clouds. This is
called condensation.
Proceed to next slide on U1L10 PowerPoint.
Water that falls to earth may follow several routes.
Proceed to next slide on U1L10 PowerPoint.
Some soaks into the ground where it can be used by plants and transpired back into the
Unit 1, Lesson 9: Environment, Ecology and Ecosystems
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atmosphere.
Some of it runs off into rivers, lakes and streams where it can evaporate.
Some will be used to replenish groundwater supplies.
Objective 3. Understand carbon cycle.
The Carbon Cycle is a complex series of processes through which all of the carbon atoms
in existence rotate.
Proceed to next slide on U1L10 PowerPoint.
Carbon is an element that is found in all living organisms.
It is very important to life.
The wood burned just a few decades ago could have produced carbon dioxide which
through photosynthesis became part of a plant. When you eat that plant, the same carbon
from the wood which was burnt can become part of you.
The carbon cycle is the great natural recycler of carbon atoms.
Unfortunately, the extent of its importance is rarely stressed enough. Without the proper
functioning of the carbon cycle, every aspect of life could be changed dramatically.
Air contains carbon in the form of the gas carbon dioxide. This carbon is captured by
plants during the process of photosynthesis.
During the process, carbon from carbon dioxide becomes part of the carbohydrate
molecules that provide food for the plant and become a part of the plant.
Animals, such as the rabbit pictured here, eat the plants and use the carbon to build their
own tissues.
Other animals, such as the fox, eat the rabbit and then use the carbon for their own needs.
These animals return carbon dioxide into the air when they breathe, and when they die,
since the carbon is returned to the soil during decomposition.
The carbon atoms in soil may then be used in a new plant or small microorganisms.
Unit 1, Lesson 9: Environment, Ecology and Ecosystems
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Objective 4. Understand the nitrogen cycle.
Nitrogen is also essential to life because it is used by living organisms to build proteins.
Nitrogen is not scarce. Nitrogen gas makes up about 78% of the earth’s atmosphere.
Proceed to next slide on U1L10 PowerPoint.
Most plants, however, can’t use nitrogen gas. Instead they depend upon nitrogen from
nitrates found in minerals in soil.
Plant roots pull nitrates from the soil.
Plants use nitrates to make amino acids, which are the building blocks of protein.
Animals and humans can then get body-building protein by eating the plants.
Remember Nitrogen is an essential nutrient to plants and plants need nitrogen for them to
grow and produce seed.
Review/Summary.
We touched on several very important aspects of what makes the earths ecosystem work.
It all works around the flow of energy which is dependant on the three cycles; the water
cycle, carbon cycle, and nitrogen cycle.
Application
Extended classroom activity:
Think about two or three foods you have eaten recently. How did the energy they contain
get from nature to you?
SAE activity:
Develop a Non-Exploratory Science Fair project with the flow of energy as the basic
concept.
Evaluation.
Student Evaluation Attached to this Lesson!
Unit 1, Lesson 9: Environment, Ecology and Ecosystems
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Answers to Assessment:
1. FALSE. The three major components are producers, consumers and decomposers.
2. C. A sequence of organisms through which food energy passes.
3. TRUE.
4. B. Respiration by producers, consumers and decomposers
5. FALSE. Amino acids are produced by plants from nitrates.
Unit 1, Lesson 9: Environment, Ecology and Ecosystems
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Student Evaluation
1. The three major parts of food chains on which humans depend are soil, plants and animals.
TRUE or FALSE?
2. Which of the following is the most accurate definition of a food chain?
A. Plants, animals and organisms that feed on each other
B. Non-living organisms that produce food for living organisms
C. A sequence of organisms through which food energy passes
D. Any group of producers, consumers and decomposers
3. Nature's water cycle is also called a hydrologic cycle and includes condensation, transpiration
and evaporation. TRUE or FALSE?
4. The carbon cycle process that returns carbon to the atmosphere includes:
A. Burning by fire and transmutation by plants
B. Respiration by producers, consumers and decomposers
C. Expiration by plants and ammonification by bacteria
D. Photosynthesis, nitrification and electrolysis
5. Amino acids, which are the building blocks of protein, are produced from carbon through a
process called ammonification. TRUE or FALSE?
Unit 1, Lesson 9: Environment, Ecology and Ecosystems
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Student Handout
Unit 1, Lesson 9: Environment, Ecology and Ecosystems
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